We report in Figure REF  the effective iron yield for the sample of clusters studied in [1]}, for the sample of groups studied in [2]}
with iron abundance measurements in the IGrM derived by [3]} and for the objects in [4]}. This plot seems to show apparently that for groups there is no discrepancy with the theoretical expectations as it is dramatically the case at the cluster scale.
The large amount of intra-cluster iron is difficult to reconcile with the metal production of stars seen in clusters today and it is posing a long standing challenge, with several unconventional solutions proposed such as a very different IMF in clusters or a significant contribution by pop III stars or pair-instability supernovae [5]}. However these results should be treated with caution as not only the measurement of \(\mathcal {Y}_{\rm Fe,\odot }\)  is prone to systematic errors [1]} but also the different trends of stellar and gas mass as a function of total mass play a fundamental role.
In particular the low baryonic fraction of groups within \(r_{500}\)  with respect to the cosmic baryon fraction does not allow to draw strong conclusions.
Clearly this plot should be more populated in particular at the mass scale of groups with robust measurements of the iron abundance consistently out to \(r_{500}\) .
